GM Service Manual Online
For 1990-2009 cars only

Object Number: 388008  Size: SF
Engine Controls Components
Cell 20: Engine Data Sensors-A/C Refrig Press, ECT, IAT, MAP and TP
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Throttle Position (TP) sensor circuit provides a voltage signal that changes relative to throttle blade angle. The signal voltage will vary from 1.0 volt at closed throttle to 4.0 volts at Wide Open Throttle (WOT).

The TP signal is one of the most important inputs used by the PCM for fuel control and most of the PCM-controlled outputs. If the PCM detects a TP signal that is intermittently below the range of the TP sensor, DTC P1122 will be set.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

    •  TP sensor indicates a throttle position signal intermittently less than 0.16 volt.
    •  The conditions is present for longer than 5 seconds.

Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives a clear code command from the scan tool.

Diagnostic Aids

Check for the following conditions:

Important: :  Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

    •  Poor terminal connection.
         Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper tension. Refer to Intermittents and Poor Connections Diagnosis , and Connector Repairs Wiring Systems.
    •  Damaged harness.
         Inspect the wiring harness for damage. If the harness appears to be OK, observe the sensor display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the sensor display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.
    •  Inspect the PCM and the engine grounds for clean and secure connections.

If the DTC is determined to be intermittent, reviewing the Fail Records can be useful in determining when the DTC was last set.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain OBD System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Select Diagnostic Troble Codes (DTCs) and note any other DTCs set.

Is DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage also set?

--

Go to DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Go to Step 3

3

Is DTC P1107 Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage also set?

--

Go to Step 6

Go to Step 4

4

Test for a poor 5 Volt Reference A circuit or TP signal circuit terminal connection at the TP sensor. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Was a problem found?

--

Go to Step 9

Go to Step 5

5

Test the TP signal circuit between the TP sensor connector and the PCM for an intermittent open or short to ground. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Was a problem found?

--

Go to Step 10

Go to Step 8

6

Test for an intermittent short to ground on the 5 Volt Reference A circuit between the PCM and the following components. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

    •  MAP sensor.
    •  EGR valve.
    •  TP sensor.

Was a problem found?

--

Go to Step 10

Go to Step 7

7

Test for a poor 5 Volt Reference A circuit terminal connection at the PCM. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Was a problem found?

--

Go to Step 9

Go to Step 8

8

Test for an intermittent open or a faulty splice in the 5 Volt Reference A circuit. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Was a problem found?

--

Go to Step 10

Go to Diagnostic Aids

9

Replace the faulty harness connector terminal(s) for the 5 Volt Reference A circuit and/or the TP signal circuit as necessary. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Is the action complete?

--

Go to Step 11

--

10

Repair intermittent open/short circuit in wiring harness as necessary. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs .

Is the action complete?

--

Go to Step 11

--

11

  1. Review and record scan tool Fail Records data.
  2. Clear DTCs.
  3. Operate vehicle within Fail Records conditions as noted.
  4. Using a scan tool, monitor Specific DTC info for DTC P1122.

Does scan tool indicate DTC P1122 failed?

--

Go to Step 2

System OK